1. Field of the Invention.
The present invention relates to radiant heaters which envelop portions of the object to be heated and, more particularly, to such heaters where the object to be heated is presented to the heater by a carrier causing the heater to open to receive the object when the carrier reaches a proper position with respect thereto.
Radiant heaters have been used for industrial purposes for a long time. They have a wide range of uses, everything from paint drying to shrinking heat-shrinkable tubes over wiring bundles or the like. In this latter use, shrinking heat-shrinkable tubing, many other methods have also been used. These include using a resistance heating clamp which can be placed around both an elongated object, such as a bundle of wires, and a heat-shrinkable tube portion positioned thereover. Another method is based on using a hot air blower which has a stream of hot air therefrom directed by the operator over surfaces of the heat-shrinkable tube portion previously placed around such a bundle of wires. A common radiant heating method is to use a radiant heater with a reflector behind the radiation source to direct the radiant energy onto heat-shrinkable tube portions placed around the elongated object with again the concentrated heat directed over the heat-shrinkable tubing.
These methods have a number of shortcomings as a means of shrinking heat-shrinkable tubing over elongated objects such as bundles of wires or optical fibers, piping, or other objects. A great deal of energy is dissipated in these foregoing methods without obtaining any value therefrom because of the repeated missing of the heat-shrinkable tubing by the radiant energy, or alternatively by the heated air stream, as the operator overshoots the edge of the heat-shrinkable tubing time after time in directing energy over the surface of that tubing.
Similarly, a clamp arrangement that must be constantly opened by an operator, and who will often leave it open, is an arrangement which leads to substantial energy losses.
An even more significant problem is the variability, sometimes leading to unreliability, in the quality of the product obtained. Thus, unsatisfactory shrinking of heat shrinkable material can occur because of a lack of operator skill or momentary inattention by the operator. This leads to the need for additional training of operators, and to additional inspection of the work product of such operators.
This need for operator skill, and constant operator concentration on the work being done, is being increased by virtue of new applications for heat shrink tubing technology. Among these is the use of a section of heat-shrinkable tubing with a solder preform provided therein. This is used, for instance, where an additional wire is to be added as a branch to the center of another main wire. By placing a heat-shrinkable tube section with the solder preform in it over the end of the branching wire and over the main wire at a location where the insulation therearound has been removed, the application of heat will cause the heat-shrink tubing to close its ends and the solder to melt. The melted solder runs to join the two wires together with the solder being prevented from flowing away from the connection region by the heat-shrinkable tubing section being shrunk.
Another growing application which requires skill and care is the providing of shrinkable tubing around fiber optic bundles. These hair-thin fibers must be handled very carefully because of their fragility. The heat-shrink tubing is also often shrunken over a splice of two ends of such a fiber and must be done in such a way that no air entrapment occurs which would reduce the support provided to the splice by the shrunken heat-shrinkable tubing.
Thus, there is a desire for a heater which can provide uniform and reliable heating of elongated objects, and particularly those having heat-shrinkable tubing thereover which is to be shrunken by heat. A heater arrangement which could be scaled up in size or down in size to handle heating a variety of objects in various settings would also be quite desirable, as would be one which could be controlled at a distance to permit use in an automated production system. Such production systems could be either batch systems or, more desirably in many situations, continuous systems. An arrangement which could be adapted for use in other kinds of elongated object heating applications would also be very useful, applications such as joining of pipe sections, heating elongated test specimens or the like.